Domestic water filters on the market come in all shapes, sizes and claims from just cleaning up dirty, yellow, turbid and/or smelly water to removing dissolved chemical substances as well. But all domestic water filters are potentially dangerous. They can be breeding grounds for microorganisms if not properly maintained. Not only is this a danger to the health of the consumer himself, but also to the public at large, as in a worst case scenario, the microorganisms can be sucked back into the public mains by back siphonage when there is a sudden drop in water pressure.

The dirty water problem has invariably brought about a flourishing domestic water filter business. The use of water filters is profligating so rapidly, particularly in the Klang Valley, that even those consumers whose tap water quality is satisfactory are also installing them. They are doing it not to keep up with the Joneses, but in case the dirty water reaches them one day as well – a sign of consumers losing confidence in the waterworks’ ability to supply water of consistent good quality.

All domestic water filters are invariably installed onto the incoming ‘service’ pipe immediately after the water meter and/or immediately before the kitchen tap. This pipe is subject to water pressure from the public mains as it is directly connected to them. Because of the importance of protecting the public from contamination in the even of back siphonage, all fittings and their installation onto this service pipe require the approval of the water authority. In Selangor, this requirement is mandated under the "Water Supply (Selangor) Rules, 1951", albeit antiquated.

Using domestic water filters which have not been approved by waterworks or other competent authority is illegal. One wonders how many filters on the market today have been approved for use and if any action has ever been taken by the authorities against this rampant infringement of the Water Supply Rules which poses a danger public health.

Water from a properly run public water supply should be fit for drinking directly from the kitchen tap. It is to ensure that our water supplies meet this criterion that the Ministry of Health (MoH) has established our drinking water standards based generally on WHO Drinking Water Standards which we have been using all along. Amongst other requirements, our MoH Standards states: "Drinking water must be clear, colourless and odourless. It must be pleasant to drink and free from all harmful microorganism, chemical substances and radionucleides in amounts which could constitute a hazard to the health of the consumers."

The rampant use of domestic water filters in the Klang Valley raises the crucial question of the extent to which the drinking water supplied by the Waterworks Department of Selangor (JBAS) has met the drinking water standards of MoH. Without published details of MoH’s surveillance programme and results of the water quality therefrom it is not possible to tell.

To get an idea of the situation, the writer has collected six water samples from homes in Kuala Lumpur, Petaling Jaya and Subang Jaya and tested them in an accredited water laboratory in Petaling Jaya. The tests were limited to determine only MoH’s aesthetic water standards relevant to dirty water problem as perceived by consumers’ senses. An additional sample of a used filter cartridge was also collected and tested in the same laboratory. Below are the details of the samples and the test results.

Table 1 – Details of water samples taken

Note: All the above samples were obtained from kitchen taps, water hoses or taps installed after the water meters and before the filters, if any.

Table 2 – Laboratory Test Results

Note: ">" = greater than; "<" = less than

Out of the six samples, three clearly failed in aesthetic aspects. They were "dirty" -- highly coloured, very turbid and contained high contents of iron, aluminium and manganese, which far exceeded the MoH’s limits.

Although iron, aluminium and manganese in drinking water do not affect health they are the cause of objectionable "dirty water" for consumption as well as staining of laundry and plumbing fixtures.

Small traces of iron, aluminium and manganese coming from water treatment works would settle and accumulate over the years at the bottom and wall of reservoirs and pipes in the distribution systems. As long as the flow pattern, both in direction and in velocity, in a water supply distribution system has been substantially the same, the accumulated layer of iron, aluminium and manganese would not slough off from pipe walls and water coming out of taps would remain aesthetically acceptable. However, if there were a reverse flow or an increase in flow, the residues would be stirred up, re-suspended and ultimately reach the consumers’ taps. The three samples of water that failed the aesthetic quality tests are believed to be from areas where there is now a constant change of flow pattern and flow rates in the distribution systems in these locations.

Clearly, the obvious solution to today’s dirty water problem is first to flush out the residues already accumulated in the distribution networks. But strategic planning is a prerequisite to effective flushing in a complex distribution system such as that in the Klang Valley, particularly in heavily built-up urban areas like Kuala Lumpur and its environs. This in turn requires comprehensive and up-to-date mappings and computer network models to do the job properly. In their absence, an effective and holistic approach to carry out flushing of reservoirs and pipelines cannot be formulated. The current approach – just waiting for consumers to complain and making feeble and ad-hoc attempts at flushing – is clumsy, out-of-date and ineffective even in arresting the localised problems of dirty water.

In addition to flushing out accumulated residues it is also obviously essential to ensure that little further residues get into the water network. It is not possible in traditional water treatment processes to completely eliminate all traces of dissolved or suspended metals in treated water – hence the limiting amounts of each substance in all water standards. But the high amounts of aluminium residues found in a used filter cartridge that was tested should be investigated, as alum, an aluminium compound, is extensively used in the treatment process. Not only will over dosing of alum result in excessive amounts of aluminium in the treated water going into the distribution, but also indicate poor operation of water treatment plants.

No matter how one looks at it, the increasing complaints of dirty water spawning the rapidly spreading and more and more fashionable use of domestic water filters in the Klang Valley do not speak very well of the operation and maintenance of the water supply systems by the waterworks. Indeed they are a sad commentary on the waterworks. Surely it is time for them to declare war on dirty water and do something before it is too late!